Thursday, 7 November 2013


 Fish are vertebrates aquatic animals,generally  poikilotherms,  most  of them are covered with scales and have fins, that permit them to move in the water and gills, which trap the oxygen  in the water.

   Fish are found in salt and in fresh water, for example the gudgeon, that lives in rivers in the mountains,  and they also live in the deep ocean, like gulper eels.

 When salmon appeared on Earth isn’t known for sure; however the information  that  exists permits scientists to know that “Teleosts ” the group of fish which salmon  belong to, dominated the water in the Cretaceous period that started  135 millions years ago. At the same time dinosaurs and other giants animals inhabited the Earth and even the oldest ancestors of  humans appeared.
The life cycle of a salmon:
 The salmons are born from eggs and live in the river. After some time they go to the sea  and when they become adults, they go back to the river to lay more eggs. The female lays the eggs and the male fertilizes them. Once they lay their eggs, they die.

Hippocampus histrix
The  Hippocampus histrix is a type of sea horse they generally live in the sea , they come from the Indian oceanic but we can find them too in the Read Sea or the Arabic sea. The Hippocampus histrix can be 15 cm in the adult age. Its body is S shaped, like most sea horses.                                                                      

The yellow tail  lady
The yellow tail lady originated in the  coral reef of the Pacific ocean. They can grow upto 15 cm. They are a blue electronic colour with a yellow tail. Their body shape is long and flattened, like most of ladies.
El hypanicistrus zebra
The Hypancistrus zebra is from Brazil, from the river Xingu. They can be from 5 to 10 cm long. Their body is flat and long, they’ve got a little mouth.

My experiment also showed the internal and external features of fish. For this I placed a sea bass on a tray. I indicated the external features like scales, fins, lateral line, operculum, eyes, mouth etc. With some tweezers I opened the operculum to see the gills. The gills are very red because they are full of capillaries with blood, ready to trap the oxygen.

 I also prepared a fish tank with fish and aquatic plants to indicate the natural gas exchange between them both producing a balance in the ecosystem.

Watch this video of our fish tank!

·       Revista national geographic (de mi casa) : el mundo debajo del agua

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